ABSTRACT
The polyethylene geomembrane industry continues to evolve and enhance material formulations to meet the challenges of demanding containment systems. There is increasing interest in characterising these geomembranes when used in critical containment applications and this is often accompanied with increased quality assurance testing. A key test used to indicate the likely durability of a polyethylene geomembrane is to measure its Oxidative Induction Time (OIT) according to either ASTM D8117 for Standard OIT or ASTM D5885 for High Pressure OIT. These tests can be undertaken on new un-aged samples, materials that have been artificially laboratory aged, or specimens exhumed from the field. Particularly with more advanced polyethylene formulations the specimen preparation procedure for OIT testing can affect the measured OIT result, making the comparison of different geomembrane formulations and the comparison of new and aged test results problematic. This paper reports on a systematic examination of different specimen preparation procedures on the measured OIT result for several different geomembrane formulations, multi-layer geomembranes and aged geomembranes. Specimen preparation procedure was also observed to have a significant effect on OIT test repeatability. Results are analysed and suggestions made regarding specimen preparation procedures for advanced geomembranes.
